In September and October of 2001, letters containing B. anthracis spores were distributed through the U.S. Postal Service resulting in contamination of the mail processing and distribution center in Hamilton, N.J., as well as affiliated processing centers in Washington D.C., New York City and Wallingford, Conn., and postal facilities along the path transited by letters mailed to a targeted media company in Florida. Subsequently, 22 individuals including postal workers, persons who received or handled the contaminated letters, and persons exposed to environments contaminated by the letters developed cases of anthrax including both the inhalation and the cutaneous forms of the disease (5, 18-20). Five of these cases of anthrax resulted in death (4, 7).
Three cases were reported of individuals developing inhalation or cutaneous anthrax infection who were not associated with any of the known infected sites. The living and work environments of these individuals showed none or only a single environmentally positive sample. It was hypothesized that these individuals may have contracted the infectious agent through contaminated mail that picked up spores when contacting a source letter, or secondary letter.
These cases raise particular questions concerning the ability of disease-causing organisms to spread through cross contamination of second and even third generation fomites in sufficient numbers to cause infection and possible death. Unfortunately, studies of the primary fomites following attacks are difficult due to their use as evidence in a criminal investigation leaving little, if any, material available for study. In addition, the owners of the contaminated fomites have a desire to have their property returned in a non-contaminated and undamaged state to protect the personal and market value of the materials. Thus, there is a need for devices and methods useful for supporting non-destructive scientific evaluation of biological agent transfer between fomites such as mailing envelopes that can simulate field activities and provide valuable information to improve protection of the public.